Ammonia supply system



Aug. 2, 1955 w. H. HOLLINGER AMMONIA SUPPLY SYSTEM Filed Oct. 9, 1952 frzz/enfofr Wafer/ H0 ZZ'z'zz oer Zmfiw, ywohgww bmmk g Patent Ofiiice 2,714,393 Patented Aug. 2, 1955 AMMONIA SUPPLY SYSTEM Walter H. Hollinger, Chicago, IlL, assignor to The C. F.

Pease Company, Chicago, 111., a corporation of Delaware Application Ucteher 9, 1952, Serial No. 313,894

3 Claims. (Ci. 137-563) This invention relates to means for supplying ammonia water to an ammonia print developer.

An example of an ammonia print developer is shown in Brunk Patent No. 2,384,155 dated September 4, 1945.

The ammonia gas is supplied to the chamber of such a developer by causing a fairly concentrated water solution of ammonia to drop onto a tray, from which is gives up its gas.

Although a gravity drip feed is the preferred means of supply, which means include a reservoir placed at a higer elevation than the drip valve, such a supply means requires filling of the reservoir from the jar in which the ammonia water is commercially delivered. This is an inconvenient operation.

The present invention contemplates the provision of a reservoir having the capacity somewhat larger than the usual gallon capacity of the commercial ammonia container, together with manually actuated means for causing the ammonia to be transferred from the jar to the reservoir. Such manually actuated means may comprise an electrically driven pump having a push button control. Thus, at appropriate intervals the suction line of the pump may be placed in a full ammonia container, and the entire contents of the container can be transferred to the reservoir.

The difliculty with such an arrangement is two-fold: first, although the entire transferring operation consumes less than a minute, the attention of the operator will sometimes wander with the result that the pump is not turned off as soon as the ammonia container is empty. Thus, the pump will run dry with the result that it will burn itself out. Even where the operator is attentive, very close attention is required in order that the pump may be turned off immediately after the emptying of the ammonia container.

Secondly, it has been found that the pump does not always operate effectively after a new ammonia container is connected to the suction line. It is not sufiicient that the pump may be designed so that the pump chamber itself will retain a small quantity of fluid. This is for the reason that the ammonia water is highly volatile. When a slight rise of temperature occurs, the gas released from the ammonia water will cause vapor lock, in the sense that positive pressure occurs in the pump and in the suction line which will prevent operation.

The present invention is designed to overcome these difiiculties: First, by the provision of an arrangement in which the pump chamber is vented and is maintained completely filled with ammonia water between successive transferring operations to the end that no substantial body of gas is entrapped within the pump or in its supply line which would cause vapor lock.

Secondly, in order to prevent damage to the pump after the ammonia container has been evacuated, means are provided to reflux at least a small amount or trickle of ammonia water to the end that the pump may be selflubricated, thereby preventing burning out of the pump. I have found that for the latter purpose, it is not essential that the pump chamber be maintained completely full, since at this stage, vapor lock is not the problem, but merely the provision of sufiicient ammonia water to pre vent the pump from becoming damaged.

The foregoing describes the principal objects of the present invention.

Another object is to provide an ammonia supply system which embodies a pump which has been found to be particularly satisfactory for operation with ammonia solution, but which is particularly susceptible to damage resulting from dry operation, and which also embodies means to prevent such dry operation.

Other objects, features and advantages will become apparent as the description proceeds.

The accompanying drawing shows a preferred embodiment of my invention, the single figure showing the relationship of the elements of the combination, certain of the elements being shown in section.

Referring to the drawings in detail, the reference numeral 1 designates a drip valve which is adapted to be disposed in operative relationship to the tray of an ammonia print developer, such as that shown in the abovementioned patent. The drip valve is connected by suitable tubing 2 to the outlet fitting 3 of an ammonia reservoir 4. It will be observed that the outlet fitting 3 is attached to the bottom wall of the reservoir at its inner end, and at its inner end includes a portion 5 which projects above the bottom wall to form a trap for a small quantity of liquid within the reservoir.

The ammonia is supplied to the reservoir 4 from a container 6, which may be the ordinary glass jar in which ammonia is sold.

The term ammonia, as used herein, refers to a water solution of ammonia. The solution purchased for ammonia print developers is usually a 26 Baum solution. Since such a solution is about 28% NH3, it is very dilficult to handle due to gas release resulting from slight changes in temperature.

The design of the standard ammonia print developer requires that the container 6 be located on the floor or in the base of the machine, thereby requiring the use of a pump 7 to elevate the ammonia from the container to the reservoir.

A type of pump which I have found to be particularly useful, both from corrosion resistance viewpoint, and from the fact that it cooperates unusually well with the other elements of the ammonia supply system herein described to avoid vapor lock, is shown in Moineau Patents Nos. 1,892,217 and 2,028,407, dated December 27, 1932, and January 21, 1936, respectively. Such a pump includes a stator 8 and a rotor 9, one of which may be made of rubber or a rubber-like composition. The stator is enclosed in a shell 10 which is confined between end pieces 11 and 12, the inlet 13 being on one, and the outlet 14 being on the other end piece. The rotor 9 is connectcd by a flexible shaft 15 to a drive shaft 16 which, in turn, is driven by an electric motor 17. Suitable push button control (not shown) may be provided for the motor as described in the introduction.

The cooperating surfaces of the stator and rotor are so shaped as to exert a positive displacement pumping action, as pointed out in the aforementioned patents, and the method of operation is such that the rotation of the rotor is eccentric to the axis of the stator, thereby requiring the use of the flexible shaft 15.

The pump 7 is connected to the container 6 and to the reservoir 4 by the following described means. A removable container fitting 20 is provided for container 6. This includes a stopper 21 through which extends a lift tube 22, a check valve 23 disposed above the lift tube, and a tube fitting 24.

Mounted on the pump inlet 13 is a T fitting 25 having a pump arm 26, a supply arm 27 and a trickle arm 28. The latter arm is provided with a constriction 23 to the end that the liquid flow through the trickle arm 28 will be cut down substantially, as will be pointed out hereinafter. The pump arm 26 of the T fitting communicates with the inlet 13 and serves as a means for supporting the T fitting as a whole.

A flexible conduit or tube 30 extends from the tube fitting 24 to the supply arm 27, thereby affording communication from the container 6 to the pump, and constituting a supply line for the pump.

A flexible conduit or tube 31 extends from the pump outlet 14 to the top of the reservoir 4, thereby constituting a supply line for the container.

Thus, when the motor is energized, the pump will cause liquid to be withdrawn from the container 6 and fed upwardly to the reservoir 4. The check valve 23 prevents reverse flow of liquid, and also permits the container fitting to be removed from an empty container and applied to a full container without loss of ammonia from the tube 30.

As pointed out above, in its intended operation, the pump is actuated only at widely spaced intervals. For instance, depending upon the size of the reservoir, and the use made of the developer, the reservoir may need refilling only once in several days. However, when a pump is used which includes a rubber pumping element such as the stator 8, any operation of the pump when it is dry will destroy the rubber element. Therefore, unless the operator is very attentive and acts to shut off a pump immediately upon exhaustion of the ammonia in the container 6, the pump will be damaged.

T avoid this, means are provided for supplying a trickle of ammonia to the pump inlet which is suificient to maintain the parts lubricated. This means includes a flexible conduit or tube 32 which extends from a suitable outlet fitting 33 located in the bottom of the reservoir 4 to the trickle arm 23 of the T fitting. Thus, there will be a constant refluxing of ammonia from the reservoir back to the pump inlet. By providing the constriction 29, the quantity of liquid reflux is so small in comparison to the liquid being pumped through the reservoir supply tube 31, that the efficiency of the pump is not materially aflfected. However, the quantity of ammonia reflux is sufiicient to lubricate the pump and prevent its burning out when the reservoir 6 has been emptied.

The second advantage of this particular refluxing arrangement is that after the pump has ceased to operate, the inlet end of the pump chamber will gradually become filled with ammonia, thereby preventing vapor lock at the time that the pump is subsequently started.

It will be observed that the outlet fitting 33 is flush with the bottom of the reservoir 4, as contrasted with the outlet fitting 3 which is provided with the trap portion 5. Thus, there will always be suflicient liquid within the reservoir to permit the inlet of the pump to become filled.

The container 6 and the reservoir 4 may be suitably vented.

A sight glass can be provided for reservoir 4 to indicate when refilling is necessary.

To summarize the operation, assuming that the capacity of the reservoir 4 is greater than the capacity of the container 6, a condition can be assumed wherein the reservoir 4 is empty, except for the entrapped liquid shown in the drawing, and the container 6 is also empty. In this condition, both the inlet and outlet ends of the pump chamber are filled with ammonia, as are the various tubes 30, 31 and 32, except for whatever gas may be entrapped at the bend in tube 30 and in the upper stretch of tube 31. The check valve 23 prevents the ammonia-in tubes 30 and 32, and reservoir 4, from running down into the container 6.

First, a full container is substituted for the empty container. Then the motor is energized. Since the inlet end of the pump chamber is full of liquid, the liquid will be displaced through the pump toward the right and upwardly through tube 31 into the reservoir 4. The resultant suction causes the ammonia from the container 6 to be lifted upwardly through the lift tube 22 and into the pump supply tube 30 and thence to the pump.

After the ammonia in container 6 has been exhausted, continued operation will not damage the pump because of the trickle of ammonia that passes through the constriction 29 and into the pump chamber.

After the motor is turned off by the operator, ammonia will continue to pass through the reflux tube and the constriction until the inlet side of the pump chamber be comes filled. The system is then in condition for another cycle of operation. In this condition the pump supply tube 30 will be empty, but the quantity of air or other gas entrapped therein is comparatively small with respect to the amount of liquid in the inlet end of the pump chamber. Thus, When the pump is again started, the volume of liquid available for displacement by the pump is sulficient to establish a column of liquid in the lift tube and in the pump supply tube 3t) prior to the time that the bubble is drawn through the pump, or is vented upwardly through the reflux tube as the case may be.

In no event can there be a positive vapor pressure in the pump supply tube 30 or in the inlet side of the pump chamber, due to the presence of reflux tube 32, which would also serve as a vent. Thus, vapor lock is pre' vented.

In the event that the pump is turned off prior to the time that the container 6 is exhausted, then the pump supply tube 30 and the inlet side of the pump chamber will be in filled condition, with the result that the reflux tube will function only as a vent to relieve the inlet side of the system from accumulation of any gas due to temperature changes, or to any other cause.

Since the reflux tube 32 serves both as a gas vent and as an auxiliary liquid supply, the simultaneous flow of gas and liquid in opposite directions is better facilitated by the provision of the constriction 29 in a tube 32 of comparatively large diameter than by providing a tube of smaller diameter with no constriction. Similarly, a constriction providing two separate openings might be preferable in some instances. In either event, the overall resistance of the reflux means to liquid flow is preferably greater than the combined resistance of the supply tube 30 and check valve 23 to compensate for the head of the reflux tube so that the amount of ammonia refluxed may be limited.

The refluxed ammonia is believed also to contribute to the efliciency of the pump since the suction sometimes causes boiling of the ammonia in the supply tube 30 with the result that the pump operates upon a mixture of liquid and gas. The refluxed ammonia serves to enrich or to add liquid to the mixture, thereby increasing the efiiciency of the pumping operation.

The provision of the trap portion 5 insures that a suflicient quantity of ammonia will always be present in the reservoir to provide for proper lubrication and for priming. For instance, if both the reservoir and container were empty and the operator forgot to substitute a full container, operation of the motor would exhaust the supply of ammonia in the inlet side or the pump chamber with the result that there would be no liquid left in the system for lubrication unless the trap portion 5 were provided. Thus, with the present invention, the pump will not burn itself out even though the container is empty and even though there is no ammonia in the reservoir available for the drip valve 1.

Although only a preferred embodiment of my invention has been shown and described herein, it Will be understood that various modifications and changes may be made in the construction shown without departing from the spirit of my invention as pointed out in the appended claims.

I claim:

1. An ammonia supply system for a print developer or the like comprising a reservoir having an inlet and an outlet, said outlet being provided with a trap portion, a drip valve connected to said outlet, a supply container disposed at a lower level than said reservoir, a pump having an inlet, an inlet chamber communicating with said inlet, and an outlet, means providing communication between said container and said pump inlet, means providing communication between said pump outlet and said reservoir inlet, whereby said pump serves to elevate liquid from said container to said reservoir, and refluxing means extending between said reservoir and said pump inlet, and including a reflux outlet disposed in said reservoir at a level lower than the level of the trap portion of said first mentioned outlet, and means providing communication between said reflux outlet and said pump inlet, said reflux communicating means providing a greater resistance to the passage of liquid than said first mentioned communication providing means whereby said pump, during normal operation, will draw the major portion of its liquid supply from said container, and whereby ammonia is refluxed from said reservoir to said pump inlet when said container is empty to avoid damage to said pump.

2. An ammonia supply system as claimed in claim 1 in which said pump inlet chamber has a larger volume than said first mentioned communication providing means.

3. An ammonia supply system as claimed in claim 1 in which said first mentioned communication providing means is provided with a check valve to prevent the reverse fiow of liquid therethrough.

References Cited in the file of this patent UNITED STATES PATENTS 2,627,875 Staege Feb. 10, 1953 FOREIGN PATENTS 335,084 Italy Feb. 1, 1936 

